This kind of an electronic circuit module includes a substrate with built-in component, mount components mounted on the substrate with built-in component, a sealing portion covering the mount components, and a shield covering the sealing portion as shown in FIG. 3 in Japanese Patent Application Laid-open No. 2009-004584. In the electronic circuit module, predetermined electronic circuits including built-in components and mount components are three-dimensionally constructed. The shield is connected to ground wiring of the substrate with built-in component, and prevents noises from outside.
Japanese Patent Application Laid-open No. 2004-63803 discloses that in a printed wiring board including a metal board and insulating resin layers disposed on both surfaces of the metal board, the metal plate is easily cut using a dicing machine while a flatness of the insulating resin layers is enhanced by forming indentations on the both surfaces of the metal plate along lines to be cut.
In general, the shield in the electronic circuit module described in Japanese Patent Application Laid-open No. 2009-004584 is formed of a metal. If the shield is formed of a conductive synthetic resin, the following defects may be induced. In other words, a bonding force between the metal and the synthetic resin tends to be lower than that between the metals or the synthetic resins. If the shield is formed of the conductive synthetic resin, the bonding force between the shield and the ground wiring made of a metal is decreased over time, which induces a local peeling at a boundary. As a result, a conduction property between the shield and the ground wiring is decreased and a desirable shield effect is not easily obtainable.
In the printed wiring board described in Japanese Patent Application Laid-open No. 2004-63803, burrs may be generated at cutting positions corresponding to four corners of the metal plate. When the burrs are contacted with wiring layers and peripheral circuits formed on the insulating resin layer, short circuit may be induced. However, there is no description about a method for preventing the burrs from being generated in Japanese Patent Application Laid-open No. 2004-63803.